In the railroad industry, couplers are used to connect adjacent ends of a pair of railway cars together. On those railway cars which will be used in interchange service, such couplers must be approved by the Association of American Railroads (AAR) prior to installation on such cars. It is well known, in this application, that such couplers serve a number of functions in addition to facilitating the connection and disconnection of individual cars to and from, respectively, a train consist. One function, for example, is to enable such individual cars to negotiate curved portions of the track structure. Further, the couplers enable such cars to be readily combined to make up such train consist, or to be readily separated individually for either loading or unloading cargo thereto or therefrom respectively. This permits a railroad to leave a particular car at a customer's plant while delivering or picking up other cargo at other locations.
In more recent times, however, the railroad industry has come to recognize that a number of rather important advantages can be gained by interconnecting several railway cars to form a generally semi-permanent unit. For example, this is particularly the case, where such individual railway cars are adapted for use in "piggyback" service. A primary reason for this is that the cargo to be either loaded or unloaded is brought to or removed from, respectively, central locations. Generally, this cargo is either over-the-road trailers or large containers. The individual railroad cars which have been joined together in this generally semi-permanent manner are commonly known in such railroad industry as a "10-pack". Except at each outer end of each 10-pack unit, these 10-pack units do not require the use of standard couplers. The primary reason why such standard couplers are not required is because of their dedicated service these 10-pack units are only broken periodically. Normally, for example, this will only occur when maintenance must be carried out on an individual coupler component or other component on the railway car that requires such car to be taken out of service temporarily. It is obvious to the railroad industry that is possible to achieve a considerable cost reduction by this coupling arrangement. Such cost-savings are derived from a variety of reasons. Such reasons include: lower equipment weight, resulting in enhanced energy savings and fewer railway trucks which results in both lower equipment cost and a reduction in maintenance requirements. However, with the now rather extensive use of these semi-permanent coupling arrangements, particularly with new cars being built for piggyback service, and with ever increasing loads being carried by modern railway cars and train consists, it has been determined that it is of the utmost importance for a close-buttoned relationship to be maintained between the coupler draft components. Such close-buttoned relationship is required, for example, so that the effects of the impact forces which are usually encountered under normal buff conditions during train operation can be reduced to an acceptable level. In this manner, damage to both cargo and equipment can be held to a minimum.
One prior art type of articulated coupling apparatus used for the purpose of connecting adjacent ends of a pair of railway cars together in a semi-permanent manner is taught in U.S. Pat. No. 4,258,628. As shown therein, this particular articulated coupling device includes a male connection member secured to one end of a first railway car body and a female connection member which is secured to an adjacent end of a second railway car body. The female connection member, in this prior art arrangement, is rotatably-engaged in a center plate bowl portion of the bolster of a railway car truck. Such rotatable engagement is carried out in a manner that is well known in the railway art. The outer end portion of the male connection member is disposed for movement within a cavity formed in the outer end portion of such female connection member. A pin member is utilized to join both the male connection member and the female connection member together in such semi-permanent fashion. This pin member is positioned in a vertical direction and is disposed in aligned apertures which are formed in each of such male connection member and such female connection member. As taught in this reference, the aperture formed in the male connection member for receiving the pin member therein must be somewhat larger than the pin member itself. This is required so that certain required movements of the coupling arrangement while in operation can be achieved. Additionally, a rear surface portion of the aperture that is formed in such male connection member, which will receive the pin member therein, has a horizontal concave configuration and a vertical convex configuration. This particular configuration will enable both the male connection member and the female connection member to move in each of a horizontal direction and a vertical direction in relationship to one another while, at the same time, this configuration provides a relatively substantial area of surface contact between the rear surface of such pin aperture and the pin member itself. The outer end surface of the outer end portion of such male connection member includes a convex configuration which abutingly engages a complimentary concave surface which is formed on a front face portion of a follower member. In this coupling device, such follower member is carried within the rear portion of such cavity disposed in the outer end portion of such female connection member. A pair of vertically-disposed, slot-like cavities are formed on such follower member adjacent the rear surface portion thereof. Disposed within each of these vertical slot-like cavities is a first portion of a resilient member. A second portion of such resilient member extends outwardly from such rear face portion of the follower member. In this manner, a portion of the exposed outer surface of each such resilient member can be engaged by a vertically disposed wedge-like element. Such wedge-like element being required in this coupling arrangement to urge the follower member and the male connection member forward. As a result, the rear surface portion of the aperture formed in the outer end of the male connection member is maintained substantially in contact with the pin member at all times.
Such contact between the pin member and the rear surface portion of this aperture in the male connection member is required in this coupling arrangement because most of the articulated connecting members used are manufactured as cast components. Furthermore, in order to achieve a reduction in the cost of this coupling device, such cast components receive very little, if any, finish-machining to provide the necessary or desirable dimensional control. In other words, these cast components are generally used as cast. As a result of this cost-saving practice, it is oftentimes difficult to provide an articulated coupling device which will be self-adjusting under the various wear conditions encountered by such coupling device during in track operation. However, it is important to minimize the slack encountered in the various coupling connections during such in track service.
Other prior art coupling devices are taught in U.S. Pat. No. 3,716,146 and Canadian Patent Number 1,231,078.